a. Field of the Invention
This invention relates to a decorative mirror unit and to a method of fabricating the decorative mirror unit.
b. Related Art
Compared with plain mirrors, decorative mirror units are relatively uncommon. One type of decorative mirror unit that has been known for many years employs two parallel sheets of mirrored float glass spaced apart in a frame. The inner, or rear mirror is fully reflecting, and the outer, or front mirror is partially reflecting, so that the viewer sees multiple superimposed images, for example of himself, fading off to infinity.
A more recent variant of this type of mirror is disclosed in patent document U.S. Pat. No. 5,137,761, in which a third sheet of clear glass is held parallel between the two mirrors. The clear glass has clear, coloured or reflective glass stones adhered to one surface of the glass, with a clear u-v curable adhesive. The glass stones can create interesting optical effects by splitting up light incident on the stones, both as viewed directly, and in the multiple images seen in the rear mirror.
A simpler version of a decorative mirror unit is disclosed in U.S. Pat. No. 5,139,828. This unit has one fully reflecting mirror in front of which is spaced in parallel one sheet of clear glass to which cut glass stones have been adhered with a clear u-v curable glue. The stones may be lit from the sides, again to provide interesting optical effects owing to scattering and diffraction of light from the stones.
In both cases, the glass stones are provided only on an internal surface of the unit so that they are protected from dirt, which would otherwise interfere with the optical effects.
An important feature of these prior art decorative units incorporating glass stone decorative elements is that the u-v adhesive is transparent so that it does not interfere with the optical effects. Glass stones can be provided with a very flat side to be affixed to the flat float glass so as to mimimise the amount of adhesive to be used. But it can be difficult to apply the transparent u-v adhesive in such a way that no bubbles are trapped whilst at the same time minimising any excess of adhesive pressed out around the edges into an unsightly bead around the decorative glass.
Whilst such decorative mirrors provide interesting optical effects, they effectively are limited in the type of decorative elements that may be applied, i.e. being limited to clear, coloured or reflective glass stones adhered on an inner protected surface of the unit with an optically clear adhesive.
It is an object of the present invention to provide a decorative mirror unit that addresses such limitations.
Accordingly, the invention provides a decorative mirror unit, comprising a mirror and at least one sheet of glass spaced in front of the mirror by spacer means, and a plurality of decorative elements applied to the glass by an adhesive means, characterized in that said sheet of glass has a pair of opposite plane-parallel surfaces and at least one optically non-transparent decorative element has been applied to each surface on opposite sides of the glass by said adhesive means, said decorative elements on opposite sides of the glass aligning to conceal at least partially the adhesive means between at least one of the decorative elements and the glass, wherein said plane-parallel surfaces extend away from a pair of said aligned optically non-transparent decorative elements on opposite sides of the glass so that a viewer can see one of said pair of decorative elements directly, and at the same time view through the plane-parallel surfaces a virtual image in the mirror of the other of said pair of decorative elements.
The glass will normally be a single unbroken sheet of glass, usually clear float glass. The decorative elements may be any type of decorative element that can be applied to glass. One type of decorative element is a strip of lead-alloy. These strips may have for convenience a self-adhesive backing. Areas between the strips, or between the strips and the edges of the window can be coloured by affixing a conveniently self-adhesive coloured plastic film, which can be transparent or translucent. The coloured film may be affixed first, so that the strips may be applied to cover the edges of the film, or the coloured film may be affixed on the opposite side to the strips, which then act as a template to guide placement of the film. Other type of decorative elements may also be applied, such as moulded, beveled or cut glass fixed in place, for example, by u-v curable glue. All such suitable items that may be affixed to a sheet of glass are referred to herein as xe2x80x9cdecorative elementsxe2x80x9d.
The adhesive means may be a bond between the decorative element and the glass, for example when the decorative element is a paint or resin applied to the glass. In this case the decorative elements conceal at least partially an adhesive interface between the decorative element and the glass. This is particularly effective when the resin is applied as a bead to the glass, the bead having a convex outer surface and a flat adhesive interface. The flat adhesive interface can then be concealed by another similar bead applied to the opposite surface of the glass.
Alternatively, the adhesive means may comprise an adhesive layer between at least one of the decorative elements and the glass, said decorative elements on opposite sides of the glass aligning to conceal at least partially said adhesive layer.
The invention therefore provides a wide latitude in the selection of adhesive means, and in general removes the requirement for there to be an optically clear or invisible adhesive interface. The adhesive means may therefore be optically imperfect, for example opaque, translucent, or contain visible defects, such as striations, bubbles or other imperfections in the adhesive interface with the glass. Such an optically imperfect adhesive means is best concealed when the decorative elements are optically non-transparent, i.e. opaque or at least translucent to some degree.
Adhesive means as viewed directly will, in general, be more noticeable than adhesive means as viewed in a reflected image, because the light will have crossed through less thickness of glass. Preferably though, the decorative elements on opposite sides of the glass align to conceal at least partially the adhesive means both as viewed directly and in the image reflected from the mirror.
There may, of course, be a slight view of adhesive means afforded through the thickness of the glass, if the decorative elements are not viewed straight on, but at a substantial angle. However, typical sheet glass is relatively thin, for example about 4 to 6 mm thick, and typical decorative elements are in most cases wider than this thickness. The decorative elements on opposite sides of the glass therefore in most cases will prevent a direct view of most of the adhesive means. In addition, when the decorative elements are non-transparent, i.e. translucent or opaque, the decorative elements will in normal lighting conditions cast a shadow between the oppositely aligned decorative elements, and this will tend to obscure or de-emphasize any slight view of the adhesive means that could be visible when the decorative unit is viewed at a substantial angle.
The minimum angle at which decorative elements may be viewed in the reflected image will in general be less shallow than what may be viewed directly. Nevertheless, it is preferable if decorative elements on opposite sides of the glass align to conceal at least partially the adhesive means in the image reflected from the mirror.
The mirror may be a conventional highly reflecting mirror formed from float glass, but could be any other reflecting surface in which an image may be seen, such as mirrored smoke coloured glass, a two way or partial mirror, or a polished metal mirror. Normally, both the mirror and the sheet of glass will be flat and parallel with each other. However, one or both of the mirror and the glass could be curved, and it is not necessary for the mirror and glass sheet to be exactly parallel.
In alternative embodiments of the invention, the mirror is concave or convex so as to respectively magnify or de-magnify said at least one decorative element spaced in front of the mirror. In particular, the de-magnifying effect can be quite striking, as this enhances the sense of depth between the decorative elements of the sheet of glass, and the image of the decorative elements visible in the mirror.
The mirror unit may be any type of portable or fixed unit, such as framed mirror suitable for mounting or hanging on a wall, a mirror in a frame adapted to be permanently set into an item of furniture such as a table top. In one application, the decorative mirror unit according to the invention may be used as part of a structure, for example a building or a conservatory, having one or more window or door apertures. At least one decorative mirror unit may then be provided within such an aperture, for example being set into a wall, door, ceiling panel or window frame.
Separating the mirror from the decorated glass surface provides a number of significant advantages. Firstly, the decoration is preferably applied to a glass surface before the glass and mirror are brought together in spaced apart relationship. This permits the use of convenient techniques in applying the decorative elements, using a template behind the glass to guide the placement of the decorative elements on the surface of the glass. Secondly, problems are encountered if the decorated glass is placed directly against the mirror, in an attempt to minimize or eliminate any gap between the glass sheet and the mirror. One of these problems is that, in practical terms, it is very difficult to get an optically satisfactory interface between a sheet of glass and another very smooth surface such as a glass or metal mirror surface. Unless index matching gel is applied between the surfaces, there may be some small layer of trapped air, for example due to dust or other imperfections, of the order of 1 xcexcm thick, which can cause interference effects with visible fringes. This would ruin the appearance of the mirror. Another of these problems is that condensation of atmospheric moisture is bound to occur in any small gap between these smooth surfaces, which could permanently affect the transmission of light across the gap.
In most cases, it is preferred if the gap is at least 0.5 mm. This separation is sufficient so that for a mirror of average dimensions of 1 m2, the glass and mirror surfaces will remain separated, even if moderate pressure is applied externally to the unit.
Larger units may require greater separations, but for most mirrors, it is preferred if the separation is no more than about 25 mm. At this separation, and taking into account any thickness of glass substrate for the mirror itself, the virtual image of the decoration produced by the mirror will be at least 50 mm behind that of the real image of the decorated glass sheet. Unless the mirror unit is particularly large, a greater separation of the real and virtual images may result in loss of usable mirror area, or a confusing and unpleasing visual effect, particularly when it is desired to see one""s image in the mirror.
In a preferred embodiment of the invention, the spacer means extends fully around the periphery of the sheet of glass so that the sheet of glass and mirror form a sealed unit. The spacer means then seals the unit. This has the advantage that conventional, low cost sealing strips may be used, such as those employed in the double glazing industry and sold by Tremco Limited under the registered trade mark Swiggle Strip. These strips permit the mirror and one or more glass sheets to be bonded into a fixed, spaced apart relationship, whilst at the same time incorporating a desiccant to prevent condensation from developing in the gap between the mirror and the glass sheet, or between the glass sheets.
In another embodiment of the invention, there are two sheets of glass to which decorative elements have been applied, one sheet of glass being spaced by spacer means between the other sheet of glass and the mirror. In this way, it is possible to build up quite complicated patterns, without the need to apply multiple layers of decoration to one sheet of glass. The inner layer of glass sheet may also be provided with more delicate decorative elements, since the outer glass sheet would protect these.
The decorative mirror unit may also be adapted to present a pseudo-three-dimensional image of a recognizable object, for example a building, a person""s portrait, an item of furniture, etc. This may be achieved if at least one decorative element applied on one surface of the sheet of glass presenting an image of a front surface of the recognizable object, and said at least one decorative element applied to the opposite surface of the sheet of glass presents an image of a rear surface of the same recognizable object, so that both the front and rear surfaces of the recognizable object may be viewed simultaneously in the decorative mirror unit.
One way in which the decorative elements may be applied is with the use of a template patterned with guidelines. The template cab be positioned under a horizontal sheet of clear glass, and left in place during the application of one or more decorative elements. This method of manufacture is efficient and reliable, but only works if the sheet of glass is transparent or translucent to the extent that the pattern on the template can be discerned. It would therefore not possible to use this method of fabrication with the sheet of mirrored glass to apply decorative elements directly onto the glass, because the template pattern could not be seen.
Also according to the invention, there is provided a method of fabricating a decorative mirror unit from a mirror, at least one sheet of glass having a pair of opposite plane-parallel sides, a spacer means and a plurality of decorative elements including at least one pair or optically non-transparent decorative elements, characterized in that the method comprises the steps of:
a) aligning the or each sheet of glass with respect to a template pattern visible through the glass;
b) applying with adhesive means at least one optically non-transparent decorative element to a first surface of the glass according to the template pattern;
c) applying with adhesive means at least one optically non-transparent decorative element to a second surface of the glass opposite to the first surface so that decorative elements on opposite sides of the glass align to conceal at least partially the adhesive means between at least one of the decorative elements and the glass; and
d) using the spacer means to set a spacing between the or each sheet of glass and the mirror so that one of said pair of decorative elements may be viewed directly and at the same time the other of said pair of decorative elements may be viewed through the plane-parallel surfaces of the glass as a virtual image in the mirror.
When decorative elements are being applied to the said opposite surface of the sheet of glass, the decoration of the first side of the glass sheet may conveniently be used as a template. In this way, decorative elements have applied to the said opposite surface of the glass may be aligned with those on the first side to conceal at least partially the adhesive means.
The spacer means may be used not just to set the spacing, but also to seal the unit.